There are various types of vacuum cleaners including upright vacuum cleaners and canister vacuum cleaners. An upright vacuum cleaner comprises two main sections namely a ground engaging portion mounted on wheels and a dirt collection portion which is pivotably mounted above the ground engaging portion. The ground engaging portion includes a cleaning head and a motor. The dirt collection portion includes a filtration means for separating entrained dirt from the intake air and means for storing the separated dirt.
Canister vacuum cleaners are substantially cylindrical in shape and comprise a rigid outer container and a hose assembly. The rigid outer container is mounted on wheels for ease of movement. The outer container is substantially cylindrical in shape and has a side which is substantially circular in cross-section. The wheels may be mounted either on the side of the container so that the longitudinal axis of the canister extends horizontally or on one end of the canister so that the longitudinal axis of the canister extends vertically. If the unit is horizontally disposed, the hose assemby is mounted on one end of the outer container. A dirt filter and collector, such as a bag, is positioned adjacent that end of the container and a motor is positioned behind the dirt filter and collector. In operation, the dirty air passes through the hose into the dirt filter and collector and the filtered air passes by the motor before exiting the vacuum cleaner. Alternately, when the vacuum cleaner is vertically disposed, the motor is mounted on top of the outer container and the motor and/or the filter means may extend into the outer container. The outer container has an air entry port to which the hose assembly is mounted. In operation, the dirty air passes through the hose into the outer container and is then filtered prior to exiting the machine.
In canister vacuum cleaners a cleaning head is attached to the end of the hose assembly distal to the entry port on the outer container. This design results in a cleaning head which is small and manouverable. However, canister vacuum cleaners have several disadvantages. If the unit is vertically disposed, the dirt will collect in the bottom of the outer container and the air entry port must be located near the upper portion of the outer container. Otherwise, the entry port would become clogged with dirt and this would decrease the efficiency of the vacuum cleaner. The motor and filter mechanism are mounted near the upper portion of the canister vacuum cleaner and accordingly the centre of gravity of the machine is relatively high. In operation, the operator typically moves these machines by pulling on the hose, which is attached to the outer container. The raised centre of gravity of the machine results in the machine being top heavy and prone to tipping. Further, since a friction fit may be used to removably mount the hose assembly in the entry port, it is occasionally necessary for the operator to cease operation and re-insert the hose to maintain a hermetic seal which is loosened by pulling on the hose assembly.
Accordingly, canister machines and in particular vertically disposed canister vacuum cleaners, can most conveniently be used within a circle having a radius somewhat smaller than the length of the hose assembly. Outside such a circle, the machine must be carefully moved from position to position to avoid tipping the machine. These machines are typically awkward to move and care is also required to avoid hitting and damaging walls and furniture.
Upright vacuum cleaners have the advantage that the motor is mounted in the ground engaging portion. Accordingly, the centre of the gravity of the machine is adjacent to the ground and the machines are not prone to tipping. In the past, these machines have typically comprised a filter mechanism which may be a cloth or paper bag. More recently, dual cyclonic upright vacuum cleaners have been developed. These upright machines utilize cyclonic action or centrifugal force to separate the entrained dirt from the intake air. As is shown in Canadian Patent Nos. 1,182,613; 1,238,869 and 1,241,158, and corresponding U.S. Pat. Nos.: 4,593,492; 4,826,515; 4,853,011; 5,160,356; 4,643,748 and 4,571,772, which are incorporated herein by reference, a cyclonic vacuum cleaner may utilize first and second cyclones which are connected in series. The first or outer cyclone is designed to remove the larger and heavier dirt particles which are entrained in the intake air and the second or inner cyclone is used to remove the finer and lighter particles which are entrained in the exhaust air from the first cyclone.
One of the disadvantages with upright vacuum cleaners is that during operation, the entire machine is continually being moved by the operator. This results in the operator becoming tired. Further, the ground engaging portion is relatively large and must be moved with care around furniture and other obstacles. Due to its size, the ground engaging portion may be too large to clean confined spaces. Thus, these machines are often designed to accept a hose assembly so that the upright vacuum cleaner may be used in a canister mode. This results in additional design complexities. Further, the operator must also carry around the hose assembly. These problems are accentuated in a commercial environment where an operator may use a machine for several hours at one time to clean large areas.
Another type of vacuum cleaner is the back-pack vacuum cleaner. Examples of such machines are the QUARTER-VAC, the MEGAVAC, the POCKET VAC, the OPTIMUS 1 and the LINEVACER. These machines have a upper portion which contains a filter bag or other filter medium. The motor is located adjacent the bottom of the vacuum cleaner below the filter means. The hose assembly is connected to the top of the machine so that the intake air passes from the top of the machine through the filter means, past the motor and is then exhausted from the machine.
Back-pack vacuum cleaners have been used in the commercial environment, and accordingly they must be worn by the operator for several hours at a time and, possibly, for an entire shift. Due to the nature of existing designs, these machines feel heavy and uncomfortable and accordingly they are not desirable for extended hours of use.